remote upgrade user package using ipkg

HI,
I have a small application added to gumstix. To update the app, I copy the .ipk, remove the old package and install the new .ipk (I remove since I dont change the version number currently)
I wish to be able to upgrade this app remotely. I plan to write a startup script which will check if internet connection is available. If yes it will try to upgrade the app. I was wondering if ipkg can directly handle this if I use version numbers, or do i need to download the ipk file manually and then run ipkg install app?

thanks
Muktabh